Footnotes ...

<1>	When there's a risk of an area code running out of phone numbers, an 'Overlay Area Code' is created that has the same geographic boundaries as the existing area code. In this case, the 540 code has been Overlayed with the 826 area code. New phone numbers in the Oak Park area will be assigned with one of these codes: 540 or 826. As a result, placing a call in the Oak Park area will require 10-digit dialing (where you enter both the area code and then the phone number).
<2>	The elevation is an estimate for the area around Oak Park - it will be higher in some places and lower in others.
<3>	Longitude & latitude values may not be the geographic center of Oak Park, rather it may be a prominent intersection or the center of population, etc. It will vary depending on the source.
<4>	Name of the USGS 7.5 Minute topographic map which includes Oak Park.
<5>	Every year, the US Census Bureau creates a population estimate for the preceeding year. Keep in mind that this value is an estimate and not an actual count. The most recent Census estimate is for the year 2019.